A prior art search uncovered the following U.S. patent references. In general, ceramic heat exchangers of the prior art have been fabricated of monolithic core structures formed by conventional methods of slip casting, isostatic pressing, cold uniaxial pressing, or extrusion; or made of corrugated paper structures saturated with ceramic slip. The principal disadvantage of these structures is that they are susceptible to catastrophic failure by cracking, particularly during daily exposure to thermal cycling. This is particularly troublesome for a solar receiver, because a solar receiver is designed to have a long life, e.g., 25 years.
U.S. Pat. No. 2,977,265, while not mentioning heat exchangers, discloses a ceramic honeycomb structure. This patent does not show the integral weaving of fluid channels into the structure as in the present invention. It further differs from the present invention in that, although it is a composite, it does not have a microcrack matrix structure.
U.S. Pat. Nos. 3,112,184 and 3,251,403 show ceramic heat exchangers but differ from the present invention in that (1) they are monolithic ceramics, not composites; (2) the fluid channels are not integrally woven into the structure; and (3) the structure is soaked in matrix before the passageways are formed, rather than after.
A secondary reference is U.S. Pat. No. 4,167,935.
In sum, the present invention offers a ceramic heat exchanger which is less expensive, has greater durability, and is less sensitive to fracture and brittleness than those of the prior art.